Assuming that a reverse at the two level by opener shows 17+ points:

With a weak hand (8 or less points), after 1X-1Major; 2Y responder re-bids:

1. their major with 5, or
2. shows preference for one of the suits.

After (1) opener's raises are inviting at the three level, to play at the four level, and asking for the Ace/King/Queen of trumps at the five level (responder re-bids: pass = none, 1st step = Q, 2^nd = K, 3^rd = KQ, 4^th = A, 5^th = AK). Opener may show a strong hand by bidding the fourth suit or by bidding the higher suit again. The fourth suit, if a major, is a strong raise, but if a minor could be four cards.

After (2), opener's raises are as above. The bid of the fourth suit, if a major, is a strong raise, but if a minor could be four cards. If the fourth suit is a minor, then opener must jump in that suit (splinter...) to show a strong raise of responder's suit. The direct raise to the three level is _asking_ for a stop in the fourth suit. Bidding the "other" suit is forcing to game and demands a cue-bid.

Example: Opener A Ax/AJTx/Jx/AKJTx Opener B AQxx/KTx/x/AKJTx

Responder A KJxx/Qxx/xxx/xxx Responder B Jxxx/Qxx/KTx/xxx

Opener A Responder A Responder B 1C 1S 1S 2H 3C (weak) 3C (weak) 3S (D stop?) 4C (no) 3NT (yes!) Opener B Responder A Opener B Responder B 1C 1S 1C 1S 2H 3C (weak) 2H 3C 4D (splinter) 4NT (spade Q) 4D (splinter) 4S (signoff) 5S (signoff) Example: Opener Qx/ KQTx/ Kx/ AKJTx Responder